Microbiology Exam 2 Review

7-1 Define the following key terms related to microbial control: sterilization, disinfection, antisepsis, degerming, sanitization, biocide, germicide, bacteriostasis, and asepsis.

Sterilization - process of removing/destroying all microbial life on an object

Disinfection - process of reducing/inhibiting microbial growth on nonliving surface

Degerming - mechanical removal of microbes from limited area

Sanitization - lowering microbial counts on eating utensils to safe levels

Biocide (Germicides) - treatments that kill microbes

Bacteriostasis- inhibiting, not killing microbes

Asepsis- absence of significant contamination

The control of microbial growth that can

Prevent infections and food spoilage

Commercial sterilization

heat treatment of canned foods to destroy C. botulinumendospores

suffix -cide

to kill

suffix -stat

to inhibit

The usual definition of sterilization is the removal or destruction of all forms of microbial life; how could there be practical exceptions to this simple definition?7-1

By commercial sterilization that kills only harmful microbes like C. botulinumendospores, not all microbes.

7-2 Describe the patterns of microbial death caused by treatments with microbial control agents.

Microbes die at steady rate and how long it takes depending on how many there are, their species and their stage. Organic matter can get in the way and longer low heat can do the same as shorter high heat.

How is it possible that a solution containing a million bacteria would take longer to sterilize than one containing a half-million bacteria? 7-2

By killing microbes at constant rate, a solution with more bacteria larger population requires more time to be eliminated

7-3 Describe the effects of microbial control agents on cellular structures.

Microbial control agents on cellular structures by damaging plasma membrane that affects its lipids and protein which changes is permeability

Would a chemical microbial control agent that affects plasma membranes affect humans?7-3

Yes, because chemical microbial control agents can damage plasma membrane and also harm proteins and DNA/RNA since humans have same cell structures

7-4 Compare the effectiveness of moist heat (boiling, autoclaving, pasteurization) and dry heat.

Moist heat is more effective because it kills microbes by denaturing enzymes while dry heat works through oxidation.